Polymer composite film with barrier functionality

ABSTRACT

Polymer composite material with barrier functionality, in particular for the use in fumigation methods, comprising at least one base polymer compound and at least one barrier functional layer, wherein the barrier functional layer comprises at least one binder that is cross-linkable and after cross-linking capable of water absorbing and gel-forming.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation application of U.S. application Ser.No. 12/175,276, filed Jul. 17, 2008, which claims the benefit of U.S.Provisional Appl. No. 60/956,755, filed Aug. 20, 2007, and U.S.Provisional Appl. No. 60/951,016, filed Jul. 20, 2007, the content ofwhich are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to polymer composite films with barrierfunctionality, methods of producing such polymer composite films andtheir use, in particular for agricultural fumigation.

2. Description of Related Art

A wide variety of polymer films like biodegradable mulch films forreducing weed growth or special biodegradable horticulture pots areknown which are used in the field of agriculture. An emphasis in theequipment of these polymer films lies in the task either to stabilizethe material against environmental and chemical influences or to improvethe biodegradability of the material.

Examples for agricultural films stabilized against pesticides with anadditive can be found in Japanese application JP 631 75 072. In theEuropean patent application EP 0214507 there are UV stabilizersdescribed which are used in films for outdoor agriculture.

Apart from that, olefin polymer films containing various types ofadditives are generally known in the art. In U.S. Pat. No. 4,538,531,for example, an improved olefin based polymer film for the use infumigation methods is described comprising a permeability reducingamount of one or more fatty acid derivatives such as stearicamide.

However, the balance between resin cost, polymer processability, filmstrength, film life span, and film barrier ability is still a challenge.

This problem is particularly acute in the area of films used forconfinement of chemical treatment agents, and especially soil treatmenttarpaulins or soil covering materials. For these and similar uses largeamount of film are used to confine chemical treatment agents to the areawhere they are applied and are desired and expected to treat. Thechemical treatment agents used, often volatile gases, tend to diffuse,wash, dissolve or blow away unless prevented from doing so. The rapidloss or escape of these treating chemicals can be undesirable forseveral reasons. For example, the chemicals may be hazardous or toxic,the desired treatment effects may not be achieved and/or lager amountsof chemicals may be required to achieve the desired effects.

The problem of providing a film fit for the use as confinement in thedescribed methods is further complicated by the fact that during usagesuch films are subjected to conditions that punctures and tears tend tooccur.

All yet known polymer films in agriculture or horticulture share theproblem that the lifespan of the confinement material is often shorteneddue to the necessity of various additives. The additives can render thepolymer films more brittle which reduces the permeability for gaseouscompounds on the one hand and the resistance to punctures on the otherhand. Furthermore, most known fumigation films are composed of barrierpolymers like poly ethylene vinyl alcohol or polyamide sandwichedbetween olefin polymer layers to keep them from swelling. Alternatively,metallised multi-layered films are used. Such multi-layered structuresshow significant stiffness together with a high tendency to roll up.Both features make the application in the field complicated and labourintensive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a gas permeator analytic cell as used inconnector with the present invention; and

FIG. 2 is a chart showing transmission rate.

SUMMARY OF THE INVENTION

Therefore, it is the object of the present invention to provide apolymer composite film preferably for the use in agricultural fumigationmethods which has an improved barrier functionality, a goodprocessability, and a long lifespan together with a reduced stiffnessand a reduced tendency to roll up.

It is another object of the present invention to provide a method forthe production of such a polymer composite film.

This object is solved by a polymer composite film with barrierfunctionality, in particular for the use in agriculture, comprising atleast one base polymer compound and at least one barrier functionallayer, wherein the barrier functional layer comprises at least onebinder that is cross-linkable and after cross-linking capable of waterabsorbing and gel-forming. In a preferred embodiment of the invention,the binder is capable of absorbing at least about 15, more preferably 25times its weight in an aqueous solution containing 0.9 weight percentsodium chloride; preferably the binder is a superabsorbent polymer, morepreferably the binder is a polyacrylate.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Under the term base polymer compound all polymer compounds areunderstood which show a sufficient UV and weather stability to withstandconstant outdoor exposure at least for 12 months and do not react withorganic biocides used in agriculture and whose properties are notchanged by the organic biocide. As the flexibility of polymer materialis dependent upon the material thickness; especially flexible films of10 μm to 250 μm thickness are understood under the term base polymermaterial.

Under the term barrier functional layer there are all polymer basedcoating layers understood which are capable of building a water barrierespecially to the permeation of fumigation gases which are emitted bydiffusion from fumigated soil. In another preferred embodiment of theinvention the barrier functional layer comprises water and asuperabsorbent polymer which is capable of a water take-up of at leastleast 100 weight % per gram polymer.

Fumigation is a method of pest control that completely fills an areawith gaseous pesticides to suffocate or poison the pests within. It isutilized for control of pests in buildings, soil, grain, and produce,and is also used during processing of goods to be imported or exportedto prevent transfer of exotic organisms. Over the area to be treated arubber or polymer film is placed. This concentrates the gases as well askeeps them from escaping and doing harm to people and wildlife in theneighbourhood.

Methyl bromide was among the most widely used fumigants until itsproduction and use was restricted by the Montreal Protocol due to itsrole in ozone depletion. Other widely used fumigants include phosphine,1,3-dichloropropene, chloropicrin, methyl isocyanate, methyl iodide,hydrogen cyanide, sulfuryl fluoride, hydrogen disulphide andformaldehyde.

Fumigation usually involves the following phases. First the area to befumigated is usually covered to create a sealed environment; next thefumigant is released into the space to be fumigated; then, the space isheld for a set period while the fumigant gas percolates through thespace and acts on and kills any infestation in the area, next the spaceis ventilated so that the poisonous gases are allowed to escape from thespace, and render it safe to enter.

Advantageously, the polymer composite material with the barrierfunctional layer of the present invention is capable of securing theconfinement of fumigation chemicals over a long period of time whilestill remaining good processability and a long life span. By employing abarrier functional layer comprising at least one binder that iscross-linkable and after cross-linking capable of water absorbing andgel-forming, the permeability of the fumigation chemicals is stronglyreduced. The inventive combination with at least one binder that iscross-linkable and after cross-linking capable of water absorbing andgel-forming for the barrier layer secures that water is (during use)absorbed but also prevents that the absorbed water is evaporated even inthe harshest conditions. Apart from that, due to the barrier coatinglayer a much easier handling of the inventive film is achieved byreducing the stiffness and the tendency to roll up.

The base polymer compound according to the present invention can beselected from the group consisting of polyethylene terephthalate,polyvinyl chloride, polyolefins such as polyethylene (such as forexample LDPE, HDPE) and polypropylene, polystyrene, polyester,polyether, polyacrylate, polycarbonate, polyamide and polyurethane whichcan optionally comprise commonly used pigments, UV stabilizers, UVabsorbers, IR absorber and light diffuser. These materials show therequired resistance to outdoor exposure and can be used in form offlexible films as wells as molded inflexible articles like trays andpots.

The barrier coating layer of the present invention is preferablyformulated from three components: binders, additives and the carrierfluid. Generally, the barrier coating layer should show the sameresistance to outdoor exposure like the base polymer compound.

Binders primarily function as an adhesive to the base polymer. Bindersare polymer adhesive systems with varying molecular weights. Themolecules in the binder can be cross-linked during the curing stage toimprove strength and create the polymer composite material.

In the preferred embodiment of the present invention the barrier coatinglayer can be based on water soluble polymer adhesive systems comprisingbinders which are cross-linkable and which are after cross-linking waterinsoluble but water-swellable and capable of gel-forming by waterabsorbing. The term “cross-linkable” according to the present inventionindicates that the binders form a network preferably initiated by heat,pressure, radiation and/or chemicals (hereinafter also referred to ashardener). The term “gel-forming” according to the present inventionrefers to a colloid structure comprising at least 50%, at least 75% andtypically at least 95% wt liquid, which is immobilized by surfacetension between it and a macromolecular network of fibres built from asmall amount of binders. In a preferred embodiment the liquid of the gelis water and the gel is a hydrogel in which water is the dispersionmedium.

The binders are preferably selected from the group comprising gelatin;alginates; cellulose based polymers such as methyl cellulose,hydroxymethyl cellulose, carboxymethylcellulose, cellulose acetatephthalate, and the like; starch based polymers such as carboxymethylstarch; natural gums, such as gum arabic, locust bean gum, carrageenangum and xanthan gum; pectins; polymers formed from acid-group containingmonomers, such as poly(acrylates) (including poly(acrylic acid),poly(methacrylic acid), and the like), poly(ethers), poly(acrylamides),poly(vinyl alcohol), maleic anhydride copolymers, poly(vinylsulfonates), hydrolyzed acrylonitrile grafted starch, acrylic acidgrafted starch, poly(N-vinyl pyrrolidone), poly(2-hydroxyethylacrylate),poly(2-hydroxyethyl-methacrylate), poly(sodium acrylate-co-acrylicacid), poly(vinylsulfonic acid), poly(ethyleneoxide), block co-polymersof ethylene oxide with polyamides, polyesters, and polyurethanes, andsalt forms mixtures and copolymers of the above.

Particularly preferred binders comprise water soluble (but aftercrosslinking insoluble) chemical and/or physical cross-linkable adhesivepolymers such as polyvinyl alcohol, polyvinyl methyl ether; polyvinylpyrrolidone; polyethylene oxide; cellulose derivatives such as dextransand starches; polyacrylates such as polyacrylacid, polyacrylamides,methyl cellulose, carboxy methyl cellulose, starch-based polymers,gelatin, casein, xanthan hydroxyl-ethyl-cellulose hydroxyl propylcellulose and/or dispersions from block co-polymers of ethylene oxidewith polyurethane.

Illustrative examples of particularly useful gel-forming, waterabsorbing cross-linkable coating binders that are capable, under themost favorable conditions, of absorbing at least about 5, morepreferably at least 10, even more preferably at least 15 and mostpreferably at least 25 times its weight in an aqueous solutioncontaining 0.9 weight percent sodium chloride are preferably selectedfrom the group comprising superabsorbers such as poly(acrylates)including poly(acrylic acid), poly(methacrylic acid), and the like),maleic anhydride copolymers, poly(vinyl sulfonates), poly(sodiumacrylate-co-acrylic acid), poly(vinylsulfonic acid), (as for exampledescribed in the US patents U.S. Pat. No. 6,737,491, U.S. Pat. No.6,849,685, U.S. Pat. No. 6,887,961, U.S. Pat. No. 7,115,321, U.S. Pat.No. 6,964,803, U.S. Pat. No. 6,808,801, U.S. Pat. No. 7,205,259),gelatin and/or dispersions from block co-polymers of ethylene oxide withpolyurethane.

A particularly useful coating material according to the presentinvention comprises the combination of at least two water absorbentcross-linkable polymer binders, wherein one water absorbentcross-linkable polymer binder is gelatin. In a particularly preferredembodiment coating layers comprise the combination of a gelatin binderand a superabsorber binder such as a polyacrylate binder.

Gelatin has been shown to be surprisingly beneficial as it supports theattachment of the water absorbent cross-linkable polymers to the basepolymer without substantially interfering with the properties of thewater absorbent cross-linkable polymers.

Any gelatin such as photographic gelatin, feed gelatin, edible gelatin,industrial gelatin, protein gelatin and so on can be used for such apreferred coating layer. By adding as an additive a hardener, thegelatin is cross-linked due to a reaction of free amino-, imino- andhydroxyl groups.

Additives are defined as insoluble pigments or low molecular weightchemicals in coating formulations that allow coatings to performspecific functions but do not contribute to the biocide function.Additives include but are not limited to pigments. Pigments aretypically the colorant portion of a coating material, but can alsoperform corrosion protection or stability in ultraviolet (UV) light.Additives also include but are not limited to non-pigments. Non-pigmentadditives include stabilizers to block attacks of ultraviolet light orheat, hardener to speed up the cross-linking reaction, co-solvents toincrease viscosity, or plasticizers to improve uniform coating.

In a further preferred embodiment of the invention, a hardener,preferably formaldehyde is used as an additive to crosslink the coatinglayer material and to improve the attachment of the layer material tothe base polymer.

A particularly useful composite material relates to a base polymerwherein the coating materials comprise a combination of water absorbentcross-linkable polymers, preferably superabsorbers, more preferablypolyacrylates, gelatin and a hardener, preferably formaldehyde.

The carrier fluid is typically a liquid such as an organic solvent orwater. The carrier fluid allows the coating materials to flow and beapplied by methods such as spraying, dipping, cascade and/or curtaincasting. This component may be in the coating formulation beforeapplication, but evaporates afterwards to allow the solid materials toimmobilize and form the polymer composite material. The polymercomposite material can optionally be dried.

The carrier fluid might therefore be completely absent, partiallypresent or present in the final, ready-to-use polymer compositematerial. In a preferred embodiment the carrier fluid is absent or onlypartially present in the final, ready-to-use polymer composite material.However, the skilled person in the art acknowledges that water oranother liquid will be absorbed by the polymer composite material duringuse and will play an important role for the functionality of the polymercomposite material.

In a further preferred embodiment of the invention water or aqueoussolutions with ethanol, aceton, 1,4-dioxane, tetrahydrofuran,dichlormethane, acetonitrile, dimethylformamide, dimethylsulfoxide,acetic acid, n-butanol, isopropanol, n-propanol, methanol, formic acidand/or other solvents known to the skilled person in the art are used ascarrier fluids.

In a further preferred embodiment of the invention, the base polymer isCorona treated to enhance the attachment of the coating layer(s) to thebase polymer.

In another preferred embodiment of the invention, the base polymer(preferably in form of a film) is at least on one side Corona treatedand comprises at least on one side at least one layer with a binder,preferably superabsorbers and more preferably polyacrylates. In apreferred embodiment, the base polymer further comprises at least on oneside at least one coating layer with an additive, preferably a hardener.In another preferred embodiment at least one of these coating layersfurther comprises gelatin. In a more preferred embodiment of theinvention all layers further comprise gelatin. In a more preferredembodiment of the invention, the base polymer further comprises at leastone coating layer with at least one organic biocide.

In another preferred embodiment of the invention, the base polymer ispreferably on both sides Corona treated and has on both sides at leasttwo layers comprising at least one coating layer with binder(s),preferably superabsorbers and more preferably polyacrylates. In apreferred embodiment, the base polymer further comprises at least onecoating layer with an additive, preferably a hardener (for closing-off).In another preferred embodiment at least one of these coating layersfurther comprises gelatin. In a more preferred embodiment of theinvention all layers further comprise gelatin.

The polymer composite material according to another preferred embodimentof the present invention can be a multilayer coating structure and thebarrier functional layer is incorporated into repeating coating layers.As an example, different binders can be incorporated in different layersor a layer can comprise different binders. A preferred embodiment of theinvention comprises a polymer composite material wherein the polymercomposite material is of a multilayer coating structure and wherein thesame or different barrier functional layers are incorporated intorepeating coating layers.

By the incorporation of the barrier functional layer into repeatingcoating layers a control of the confinement rates is even betterachievable. Apart from that, different barrier functional layers can beincorporated so that even scratches and superficial damages of the filmdo not impart the safe containment of the potentially hazardouschemicals. It is known that all other fumigants besides methyl bromideand methyl iodide have a lack of effectiveness on pest management insoil fumigation. In another preferred embodiment of the presentinvention an organic biocide is added to the barrier functional layer.

Like that, the coating layer can not only confine the fumigationchemicals and thus reduce the amount needed for effective treatment butit can also prevent the soil from being infested again. Accordingly,even less chemical is needed to achieve the desired effect.

The organic biocide is preferably selected from the group consisting ofpesticides, herbicides, insecticides, algicides, fungicides,moluscicides, miticides, and rodenticides. Moreover, the organic biocidecan even more preferably be selected from the group consisting ofgermicides, antibiotics, antibacterials, antivirals, antifungals,antiseptics, antiprotozoals and/or antiparasites as well as mixturesthereof.

In another preferred embodiment of the invention the organic biocide isselected from the group of antiseptics and/or disinfectants for medicaluse and food as well as mixtures thereof.

As the regulations for chemical substances being considered safe for theuse in the agricultural, food and medical field are constantly changing,such organic biocides are most preferred for the present invention whichcomply with the actual official regulations for chemical substances andespecially for antiseptics and disinfectants in those fields.

Especially those substances which are listed in the European theBiocidal Products Directive (98/8/EC) by the European Commission arepreferably used as organic biocides according to the present invention.

In another preferred embodiment of the present invention the organicbiocide is selected from the group comprising acetamides and anilidesherbicides like alachlor, acetochlor, metolachlor, naproamid, carbamateand thiocarbamate herbicides like asulam, terbucarb, thiobencarb,chlorphenoxy herbicides like 2,4,-D, 2,4-DP, 2,4-DB, 2,4,5-T, MCPA,MCPB, MCPP, dicamba, dipyridyl herbicides like paraquat, diquat,nitrophenolic and dinitrocresolic herbicides like alconifen,oyxfluorfen, rimsulfuron, trifloxysulforon, cyclohexyloxim herbicideslike clethodim, sethoxydim, phosphonate herbicides like glyphosate,glyfusinate, fosamine ammonium, triazine, triazone, traizolon herbicideslike simazine, cyanazine, metribuzin, carfentrazone, urea herbicidederivatives like diuron, flumeturon, linuron, haloulfuron,ethoxysulforon, antibiotics insecticides like abamecitin, spinosad,cyclodien insecticides like endosulfan, insect growth regulators likepyriproxfen, carbamate insecticides like methomyl, oxamyl, nicotenoideherbicides like imidacloprid, pyrethroid herbicides like cyfluthrin,esfenvalerate, lambda-cyhalothrin, oxadiazine insecticides likeindoxacarb, organophosphorus insecticides like methamidophos, acephate,naled, malathion, acetamide and anilide fungicides like mefenoxam,boscalid; fenhexamid, aliphatic nitrogen fungicides like cymoxanil,aromatic fungicides like chlorothalonil, dichloran, carbamate andthiocarbamate fungicides like mancozeb, maneb, propamocarb, thiram,conacol, myclobutanil, imidazole, morpholin and oxazol insecticides,thiophanate, dimetomorph, famoxadone, organophosphorous fungicides likefosetyl, phatlimid fungicides like captan, strobillurin fungicides likeazoxystrobin, pyraclostrobin, trifloxystrobin, azibenzolar, ureaderivative fungicides like bentaluron, pencycuron, oquinazamid,quaternary ammonium antiseptic compounds like benzalkonium chloride,cetyl pyridinium chloride, quaternary ammonium related antisepticcompounds like chlorhexidine gluconate, polyhexamethylene biguanidehydrochloride and octenidine dihydrochloride.

Most preferably, the organic biocide of the present invention is anon-liquid non-oil substance at room temperature with low volatilitywhereby the substance is solid or formulated in solid form. The choiceof such substances improves the release controllability and the storagestability of the polymer composite material. Especially, essential oilsas organic biocides should be avoided because of the difficulty toprovide an even dispersion in the polymer base compound. Furthermore,the mechanical stability of the polymer composite material could bedeterred in the production process due to bubble wrap and the like ifliquids or substances with high volatility would be incorporated.

In another embodiment of the present invention the polymer compositematerial can withstand at least 24 months of outside exposure tosunlight and weather. That is independent on whether there is a coatinglayer present or not. By having such a minimum resistance the polymercompound is sure to fulfil the requirements of the intended use inagriculture as fumigation or mulch film, for instance.

Likewise, the polymer composite material should not be biodegradable.The function of the polymer composite material should be usable over along period of time so that for example no weeds, pests or fungi canharm the plants as they grow in a field under the protection of thepolymer composite biocide material. Furthermore, the articles of theintended use like films should be useable over a wider period of timeand should not degrade in one planting and harvesting season, forexample. Especially the mechanical stability of the films should be kepthigh because the film should preferably be retractable from the fieldand reusable.

It is within the scope of the present invention that the inventivepolymer composite material comprises additional pigments, additives andfillers which are widely known to the skilled person.

In another preferred embodiment of the present invention the barrierfunctional layer is capable of absorbing water to comprise a waterbarrier of at least 0.4 mm thickness. Thus, a minimal confinement can beprovided even over a long period of time and in hot weather conditions.

Preferably the thickness of the whole coating layer with binder(s),preferably superabsorbers and preferably also with gelatin is between1-100 μm, preferably 5-40 μm, and particularly preferred 10-30 μm. Thewhole coating layer can be produced by coating several layers ofbinder(s), preferably superabsorbers and preferably also gelatin forexample with cascade or curtain casting. The thickness of the wholecoating layer with the additive, preferably the hardener is 0.2-5 μm,preferably 0.5-3 μm, even more preferably 2-3 μm. The whole coatinglayer with the additive, preferably hardener and preferably also withgelatin can be produced by coating several layers of the hardener andpreferably with gelatin for example with cascade or curtain casting.

The base polymer has a thickness of 10 to 250 μm, preferably of 20 to120 μm, more preferably 20-50 μm.

Another subject of the present invention is a method for the productionof a polymer composite material according to the present inventionincluding the step of

-   -   coating the base polymer compound with at least one barrier        functional compound comprising a carrier fluid and a binder,        preferably a superabsorbent polymer, more preferably a        polyacrylate polymer and curing the mixture to give a coating        layer.

The “barrier functional compound” preferably further comprises gelatin.In a preferred embodiment of the invention, binders, preferablysuperabsorbers, more preferably polyacrylates, gelatin and as anadditive a hardener are used as barrier functional compounds.

The coating compounds can be applied to the workpiece made of the basepolymer in a variety of ways. Coatings compounds can be sprayed over thepart, or the part can be dipped into a tank of coating material. Othermethods include showering parts with coatings or rolling parts betweenlarge barrels to spread on the coating.

Cascade casting or curtain casting advantageously allows the applicationof multiple layers, also of different thicknesses, onto the polymercomposite material in a one work step.

The application of the coating layer is preferably carried out bycurtain coating. The method of curtain coating is well known in thefield of photographic films and papers and can be advantageously appliedto the coating of the present invention. Improved methods of curtaincoating procedures that can be used to produce the polymer compositematerial of the present invention includes such procedures as they aredescribed in EP 1 023 949 A1, EP 938 935 A2, U.S. Pat. No. 5,906,865, DE195 00 402, and EP 275 015 B1, which are therefore incorporated byreference.

In the process of curtain coating, a base film or paper web is movedcontinuously by a transport device through a coating zone and is therebycoated with one or more layers either wholly or partially by thefree-falling liquid curtain.

In the photographic industry, this process is used, for example, toapply photosensitive and photoinsensitive coatings. These coatingscomprise mostly multiple layers formed from aqueous coating solutionswhich are coated as layer composites in the liquid state onto the base.The curtain in the curtain-coating process can be wider or narrower thanthe base. The base of the photographic application is mostly a syntheticfilm or a paper web. Coating speeds can vary in accordance with the basematerial and thickness and with the thickness of the liquid curtain andits viscosity, for example. In so called high coating speed applicationsthe photographic coating solutions can be applied at a base speed frommore than 250 meters per minute. The coated base then passes through adrying device in which the coating solution is dried. The dry film webis wound up. At this point, the edges of the web must be dry or else theindividual layers of the roll will adhere.

With the advantageous possibility of producing the polymer compositematerial of the present invention by curtain coating the base polymercompound with the coating layer comprising carrier fluid, binder(s),preferably a superabsorbent polymer and optionally gelatin and/oradditives, high production speed and low cost bulk production can beachieved.

In a preferred embodiment, curtain coating on a preferably Coronatreated base polymer with a coating comprising a binder, preferably asuperabsorber and a carrier fluid is conducted. In another preferredembodiment, the coating with the binder further comprises gelatin. In anadditional preferred embodiment, a hardener as an additive is addedshortly before curtain coating to the coating. A further preferredcurtain coating method is conducted with a second coating comprising asan additive a hardener with a carrier fluid. In another preferredembodiment, the second coating comprises gelatin, a carrier fluid and ahardener as an additive and the hardener is added to the gelatin shortlybefore the curtain coating. A further preferred curtain coating methodis conducted with a third coating comprising at least one biocide andoptionally gelatin and a carrier fluid.

Preferably, the method according to the present invention comprises thefurther step of coating both sides of the base polymer compound with adifferent mixture each comprising at least one barrier functional layer.

Like that, it is possible to incorporate different barrier functionallayers, one for instance for the direct uptake of chemicals diffusedfrom the soil and the other one as further confinement layer on theouter surface of the film.

As already shortly mentioned above, a polymer composite materialaccording to present invention or a product obtained by a methodaccording to the present invention can be preferably used in agricultureas confinement film for fumigation methods.

The invention also relates to mulch film, fumigation film, propagationfilm comprising a polymer composite material as discussed herein.

FIGURES

FIG. 1: Schematic design of the gas permeation analytical cell

-   -   Legend: 1: Feed Gas; 2: thermostated; 3: Pressure Gauge; 4:        Exhaust Gas; 5: to quadrupol mass spectrometer; 6: to vacuum        pump; 7: Pressure Gauge; 8: Film; 9: Porous Metal Plate; 10:        Shut-Off Valve (accumulation volume between shut-off valves=6.95        cm³); 11: Purge Gas

FIG. 2: Overall transmission rate

EXAMPLES Example 1 Manufacturing of Propagation Films

Propagation films by coating a polyethylene film with followingadditional layers was manufactured by using curtain casting machine:

Film 1:

Base: Corona treated 100 μm thick Low-density polyethylene (LDPE)polyethylene film

First layer: 9.36 g/m² superabsorber S1 (flexible absorbent bindercomposed of: 20-40% by weight Sodium Polyacrylate (CAS-No.: 9003-04-7),2-5% by weight polyethylene glycol (CAS-No.: 25322-68-3), water(CAS-No.: 7732-18-5) dissolved in 53.40 g water

-   Second layer: 9.36 g/m² superabsorber S1 dissolved in 53.40 g water-   Third layer: 9.36 g/m² superabsorber S1 dissolved in 53.40 g water-   Fourth layer: 9.36 g/m² superabsorber S1 dissolved in 53.40 g water

Film 2:

Base: Corona treated 100 μm thick Low-density polyethylene (LDPE)polyethylene film

-   First layer: 9.36 g/m² superabsorber S1    -   and 3.12 g/m2 gelatin dissolved in 53.40 g water-   Second layer: 9.36 g/m² superabsorber S1    -   and 3.12 g/m2 gelatin dissolved in 53.40 g water-   Third layer: 9.36 g/m² superabsorber S1    -   and 3.12 g/m2 gelatin dissolved in 53.40 g water-   Fourth layer: 9.36 g/m² superabsorber S1    -   and 3.12 g/m2 gelatin dissolved in 53.40 g water-   Fifth layer: 2.34 g/m2 gelatin dissolved in 27.53 g water-   Sixth layer: 1.20 g/m2 gelatin    -   1.33 g/m2 hardener H1 (formaldehyde, concentration: 10% in        water; coating amount 0.086 g hardener H1 per g gelatin).        Gelatin and hardener are premixed shortly before curtain coating        with 28.20 g water

Film 3:

Base: Corona treated 100 μm thick Low-density polyethylene (LDPE)polyethylene film

-   First layer: 9.36 g/m² superabsorber S1    -   and 3.12 g/m2 gelatin dissolved in 26.70 g water    -   Second layer: 9.36 g/m² superabsorber S1    -   and 3.12 g/m2 gelatin dissolved in 26.70 g water-   Third layer: 9.36 g/m² superabsorber S1    -   and 3.12 g/m2 gelatin dissolved in 26.70 g water-   Fourth layer: 9.36 g/m² superabsorber S1    -   and 3.12 g/m2 gelatin dissolved in 26.70 g water-   Fifth layer: 2.34 g/m2 gelatin dissolved in 27.53 g water-   Sixth layer: 1.2 g/m2 gelatin, 1.33 g/m2 hardener H1 premixed    shortly before curtain coating with 28.20 g water.

After coating, the films were dried

Example 2 Mechanic Stability of the Films

Than, the films prepared according to example 1 were soaked for 10minutes in distilled water. Subsequently, excessive water was drainedand the mechanic stability was tested by washing-up the soaked layerswith flowing warm water. Whereas the superabsorber S1 layers dissolvefrom the polyethylene layer in film 1, the additional layers in films 2and 3 do not dissolve from the polyethylene layer.

Example 3 Permeability of the Films for Methyl Bromide AnalyticalProcedure:

Gas permeability of coated (see example 1) and uncoated low-densitypolyethylene (LDPE) films were measured by manometric determination ofthe permeating quantity of gas (by measuring the increase in pressure)and in situ determination of the gas composition using a connected massspectrometer for multigas measurements

Description of the Analytical Device:

The analytical device used is a gas permeation cell from Mecadi GmbH(Homurg/Saar). This analytical cell consists of twotemperature-controllable stainless steel cylinder heads, between whichthe film to be analyzed is clamped in a gastight manner. The film issealed against the two cell halves by pressing a Viton O ring into thefilm material from both sides. On the receiving side the film materialrests on a porous sintered metal plate in order not only to guaranteethe mechanical stability of the film even when a considerably higherabsolute pressure is present on the source side than on the receivingside, but also to ensure that no significant reduction occurs in thefree film area available for permeation. High precision pressure sensors(0.1 mbar resolution) for recording the changes in the absolute pressureare screwed into both cell halves. The receiving side of the cell can besealed towards the exterior (see FIG. 1) by three VSM precision meteringvalves (leak rate: <1-10⁻⁹ mbar*l/sec). The volume of the receiving sideis determined once by gas-pyknometric analysis and a connectedaccumulation volume.

Procedure for Standard Analysis:

The analytical cell is kept at a constant temperature of 25.5 (+/−0.2)°C. The temperature on the receiving side is continuously recorded. Afterinserting the film, the analytical cell is purged on the source sidewith an inert gas for at least 30 minutes and evacuated on the receivingside down to the final pressure of the vacuum pump (about 2 mbar). Thenthe gas or gas mixture to be permeated (the feed gas) is introduced intothe source side. The gas perfuses the source side at a constant rate of20 sccm for the entire duration of the gas accumulation process on thereceiving side. About at least 20 minutes after beginning to introducethe feed gas into the source side of the cell the valves leading to thepump and to the mass spectrometer are closed and the gas accumulationprocess begins on the receiving side. The increase in pressure on thereceiving side is recorded as a function of time by a connected measureddata logger. After allowing gas to accumulate for several hours thevalve leading to the mass spectrometer is opened and the accumulated gascomposition on the receiving side of the cell is analyzed. The ionstreams determined by the mass spectrometer are quantified by priorcalibration measurements. The oxygen content of the gas atmosphere isalso examined in order to determine whether air has penetrated thereceiving side of the cell from the exterior due to leaks.

Special Analysis using a Film Moistened on the Source Side:

In order to moisten the film to a specific degree prior to thepermeation analysis it is moistened by sweeping the source side withnitrogen at a rate of 20 sccm. For this purpose the nitrogen is bubbledthrough a water column of a height of 10 cm before being introduced intothe permeation cell. By means of this process relative humidity of about50% is produced on the source side. The duration of this pre-treatmentis at least 12 hours. Then the moist nitrogen is replaced by drynitrogen by allowing dry nitrogen to flow through the source side of thecell for 10 minutes. During this pre-treatment period the receiving sideof the cell is permanently evacuated.

Permeation experiments were performed with nitrogen and a gas mixture of5 Vol. % MeBr in nitrogen. Test results were obtained for LDPE films byMeBr/nitrogen permeation at dry and moist conditions.

Overall permeation (MeBr/N2 Mixture) is reduced by a factor of 50-100 bycoating the LDPE films. Overall permeability (MeBr/N2 Mixture) is notsignificantly effected by moistening the coated film before permeation(see FIG. 2).

What is claimed:
 1. Polymer composite material with barrierfunctionality comprising at least one base polymer compound and at leastone barrier functional layer, wherein the barrier functional layercomprises at least one binder that is cross-linkable and aftercross-linking, said binder is capable of water absorption and/or isgel-forming.
 2. Polymer composite material according to claim 1, whereinthe binder is capable of absorbing at least about 15, times the weightthereof in an aqueous solution containing 0.9 weight percent sodiumchloride.
 3. Polymer composite material according to claim 1 wherein thepolymer composite material comprises a multilayer coating structurewherein the same or different barrier functional layers are incorporatedinto repeating coating layers.
 4. Polymer composite material accordingto claim 1, further comprising at least one coating layer and an organicbiocide is incorporated into said coating layer.
 5. Polymer compositematerial according to claim 4 wherein the organic biocide is at leastone selected from the group consisting of pesticides, herbicides,insecticides, algicides, fungicides, moluscicides, miticides,rodenticides, germicides, antibiotics, antibacterials, antivirals,antifungals, antiseptics, antiprotozoals, antiparasites, antiseptics anddisinfectants.
 6. Polymer composite material according to claim 1,wherein the base polymer compound is selected from the group consistingof polyethylene terephthalate, polyvinyl chloride, polyolefins such aspolyethylene and polypropylene, polystyrene, polyester, polyether,polyacrylate, polycarbonate, polyamide and polyurethane.
 7. Polymercomposite material according to claim 4, wherein said at least onecoating layer comprises gelatin.
 8. Polymer composite material accordingto claim 4, wherein said at least one coating layer comprises at leastone additive.
 9. Polymer composite material according to claim 4,wherein said at least one coating layer comprises at least one carrierfluid.
 10. Method for the production of a polymer composite materialaccording to claim 1, comprising: coating the base polymer compound withthe barrier functional compound comprising a carrier fluid and a binder,and curing the barrier functional compound comprising said carrier fluidand said binder to form a coating layer.
 11. Method according to claim10 wherein the method further comprises coating at least two sides ofthe base polymer compound with a different mixture, each comprising atleast one barrier functional layer.
 12. Method according to claim 10,wherein said coating comprises curtain coating.
 13. A method accordingto claim 10, adopted for use in agriculture and/or horticulture.
 14. Amethod of claim 13, wherein said method involves mulch film, fumigationfilm and/or propagation film.
 15. Mulch film, fumigation film and/orpropagation film comprising a polymer composite material according toclaim
 1. 16. Material of claim 2, wherein said binder comprises asuperabsorbent polymer.
 17. Material of claim 2, wherein said bindercomprises polyacrylate.
 18. Material of claim 8, wherein said additivecomprises a hardener.
 19. Material of claim 8, wherein said additivecomprises formaldehyde.
 20. Material of claim 9, wherein said fluidcomprises water and/or an organic solvent.